MANAGEMENT OF A PHOSMET-CHARGED DIPPING VAT AND THE CONTROL OF BOOPHILUS-ANNULATUS

An 11.6% emulsifiable concentrate of phosmet (Prolate(R)) was evaluate d in a dipping vat to determine its stability and other characteristic s pertaining to management of the product in a vat in which large numb ers of cattle were processed. A separate trial was done to determine e fficacy of the product for the control of Boophilus annulatus (Say) on cattle. In the vat management test, triple superphosphate, CaH4(PO4)( 2), was added to the vat contents during the initial charge to maintai n an acidic pH. The phosmet in the vat remained stable while 2,303 hea d of cattle were dipped over the 5.5 mo test period. The pH remained b etween 3.6 and 5.3 without adding additional buffer. Phosmet is stripp ed as vat contents are carried out of the vat on the bodies of treated cattle; the vat was replenished at the manufacturers recommended rate five times during the test. The efficacy of five concentrations (0.01 , 0.02, 0.05, 0.10, and 0.12% AI) of phosmet were tested. The two lowe st concentrations controlled 97.9 and 99.9% of the ticks; concentratio ns of 0.05% AI or higher provided 100% control.